Many medical applications, in the field of imaging for example, but also for invasive interventions, need extremely strong magnetic fields which are frequently created by superconductive magnets. In addition to magnetic resonance imaging, field-based navigation systems for controlling invasive instruments introduced into the body could be cited as examples.
With these types of applications with high magnetic fields metal objects introduced unintentionally and/or without being discovered, especially ferromagnetic metal objects, represent a great risk. Moving metal objects represent an appreciable risk of injury.
There are thus known procedures for explaining these risks to patients in order to then request them to remove all metal objects. In addition the patient has to be asked about metallic implants. Furthermore it is also normal to examine patients or to scan them with a hand-held metal detector.
Such processes however require a patient who is able to respond or whose mental faculties are unimpaired. However it is occurring ever more frequently that the patient is subjected to such magnetic fields from time to time during the course of medical interventions. It is known for example that control images are recorded after or during an open intervention, for example an operation, in a magnetic resonance system. To this end the patient is generally placed on a patient support plate from which he must not be removed during the entire process. For this purpose the patient support plate can be moved by means of a patient transport means, typically a trolley, to different intervention and/or imaging locations where the patient support plate can then for example be pushed onto an operating table or onto the patient table of a magnetic resonance system. For example embodiments are known in which the patient support plate can be pushed from the patient transport means arranged on the foot side of the table in the longitudinal direction onto the patient table (i.e. a patient support means).
The patient is thus arranged permanently on the same patient support plate during the entire medical intervention and associated examinations and is mostly not able to respond. This increases the risk of metal objects on or in the patient or on the patient support plate being overlooked. In order to prevent this, working procedures are known so that for example the medical/surgical instruments employed are counted or the operation area is searched by hand and visually by the medical personnel. Despite this, especially with objects which are hidden, errors can occur in these cases and objects can be overlooked, which then present a risk of injury.